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Heating of XB-70 vs. SR-71
The SR-71 was made with not tightly fitting fuel tanks and black paint, etc. to deal with aerodynamic heating. The XB-70 flew at essentially the same altitude and speed range, and was designed with not so leaky tanks and pure white painting. Illustrations with temperature data showing nearly the same temperature on the skin of the planes. So how it is possible that these two planes designed to fly in similar circumstances are so differently handling with the heating?

The Blackbird may have been a bit faster.

So how it is possible that these two planes... are so differently handling with the heating?

Different materials built in different ways.
The only materials able to sustain high temperature without losing their structural strength are titanium alloys, stainless steel and nickel alloys.

(Specific strength versus temperature, source)
The Blackbird mainly used titanium for its structure (and some special kind of plastic to reduce its radar signature), as explained for example in this answer.
The X-15 used nickel alloys to resist flights at Mach 7.
North American Aviation engineers used a different approach to tackle high temperature and expansion when designing the XB-70. They used titanium alloys for the substructures (some 9% of its structural weight) and the much cheaper and easy to work stainless steel for the rest of the structure (some 70% in weight). Anyway the stainless steel was not used in the form of simple panels like in a standard aircraft (Blackbird included) but they arranged it in "brazed stainless steel honeycomb sandwich panels": basically two sheets of very strong stainless steel alloy with a honeycomb structure between them, all brazed together.

(Cropped image from the original on USAF museum)
These panels were very light (since they were made up of thin sheets), strong (since they had a big total thickness) and insulating (since there was a lot of air between the two sheets). But getting them right was not easy: skin detachments at high speed was initially a big problem with pieces as big as 1 meter detaching and hitting other structures. But eventually this problem was (almost) completely solved improving the fabrication process.
Fuel tanks were sealed with a special rubber and pressurised with nitrogen to avoid auto-ignition: gas-tightness also proved to be a challenge at the beginning but was eventually mastered too, with several layers of rubber applied and cured in a specific way.
Note that the two XB-70 built logged only a total of 1:48 hours at Mach 3+: basically nothing in respect to the Blackbird, so it is not possible to say if this construction technology would have been better or worse than the Blackbird's one.
But from a metallurgy point of view, the Valkyrie taught a lot of valuable lessons still in use today.

Regarding the colour: I agree with the answer of @fooot, i.e. it is normally chosen according to the mission. The Blackbird was mainly flown at night and a dark colour (which was actually blue and not black) made sense with the bonus point of helping in radiating heat.
The Valkyrie was supposed to drop nuclear bombs so it was painted in a bright "anti-flash" colour.

The supersonic flight regime of the Blackbird was no longer than that of the Valkyrie, limiting factor being the fuel capacity. No significand difference there.

@Jpe61 I read Sophit's answer as the total accumulated flight time at Mach 3. With such limited exposure much less experience with deformations resulting from high temperature could be gathered. Remember that the XB-70 was shedding panels in early flights, requiring improved brazing techniques.

Oh, that may very well be what sophit ment @PeterKämpf however I'm under the a firm belief that the problems were solved, and the design was "ready" in structural sense. It was the shift towards ICBMs that killed the Valkyrie, not technical limitations.

@Jpe61: yep, this is what I meant. ICBMs and the competition from the Blackbird itself.

Thank you very much for this detailed answer. In the end, for reducing the B-70's infrared signature, it was said by most sources, including Jenkins & Landis 2003, that it would be painted in a silver coating. So yes, I also think the color is not as important as I thought earlier. I did not realize the special features of the honeycomb structure, such as its rigidity and air content for better heat insulation.

@magalenin: thanks for choosing my answer  Yep, people at North American Aviation knew what they were doing. It is not by chance that they developed (list from Wikipedia) the X-15, the XB-70, the B-1, the Apollo command and service module, the second stage of the Saturn V rocket, and the Space Shuttle orbiter

While black surfaces emit heat more efficiently than lighter colours, this was not the only reason for the colour of the Blackbirds.
Earlier iterations of the A-12, the predecessor of the SR-71, were mostly bare titanium externally. The black coating added later was not just any high temperature paint, it was a special compound containing small metallic particles to reduce the reflectivity of the surface in the radar spectrum.
The Blackbirds handled the heat expansion by corrugation of the flat surfaces. This added necessary rigidity to avoid buckling of the panels that would have ruined aerodynamics.
The leaky tanks of the SR-71 were a consequence of weight saving measures more than anything else. To save weight, the fuel tanks were integral to the structure. Bladders or sealants could not be used due to the heat, so the slight gaps left to allow for thermal expansion leaked when the airframe was in ambient temperature.
The XB-70 construction was different from the Blackbirds'. It was made of stainless steel honeycomb sandwich panels, which are inherently rigid, and did not need corrugation or expansion gaps. As for the color, had the XB-70 ever matured into B-70, it would have most likely been painted with the same black compound as the Blackbirds were. The white coloured Valkyries we have seen are white, because they are/were prototypes. The program was cancelled before the aircraft was ready for service.
(source)

Ben Rich said in his memoir the black paint was partly for temperature control.  Are there later sources that say it was only an anti-radar coating?

@ErinAnne I think I must edit my answer, since your source quotes the highest possible authority in this case, Clarence Johnson, in a credible way. Thanks for bringing this up! I'll check my "archives" first and get back to this.

Thank you, with regard of the importance of the painting.

At the time, strategic bombers were usually bare metal or white as it was thought it's help reflect the flash from a nuclear detonation near the aircraft, reducing damage. A production B-70 would likely have been bare metal, like the B-47 and B-58.

Could be, then again, B-70 was stupid fast compared to even the Hustler, so the composition and as thusly the color of the paint may have eventally been chosen differently, might have to draw a geometeic comparison of this. The heat blast would have reached the Valkyrie from behind, at an angle that may have made the white paint (or bare metal) not necessary.

The color of the aircraft was decided primarily based on the military mission, not for temperature. Black helped the SR-71 blend in better at night and high altitudes, and the paint was also designed to make it less visible to radar. White was chosen to protect the XB-70 from the bright flashes of its nuclear weapons.
While the color may have made a difference for temperature it probably wasn't critical. Darker colors radiate heat better, but they also absorb more heat radiation. The primary means of addressing the temperature issue was using titanium for leading edges and circulating fuel to cool hot surfaces.
Also, the critical limit for the SR-71's speed was not necessarily the structural temperature, but the engine compressor inlet temperature.
As for the fuel tanks, the XB-70 wasn't free of leaks either.
Also note that the aircraft were not equally proven designs. There were only 2 XB-70 prototypes that flew for just over 3 years, while there were 32 SR-71s built (plus 18 of the related variants) that continued to fly for 45 years. The XB-70's fastest flight reached Mach 3.08 while the SR-71 reportedly reached as high as Mach 3.5.

Yes! Anti-flash white, just like the TSR2! +1

In the end, for reducing the B-70's infrared signature, it was said by most sources, including Jenkins & Landis 2003, that it would be painted in a silver coating. So yes, I also think the color is not as important as I thought earlier. Thank you.


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Why are the back of the wings of some aerobatic planes swept forward?
I've seen that in some aerobatic planes like the Edge 540, the back of the wings are swept forward. Why is that? Does it help in maneuverability?

Photo from https://en.wikipedia.org/wiki/File:Edge_540_In_Flight_1.jpg

With the engine in the front those planes tend to be a bit front-heavy. By making the leading edge straight and trailing edge swept-forward, the center of lift could be moved forward a bit.

Look at where the pilot is sitting.

It's fascinating that there are a number of completely different thoughts on this matter, unusual for this site!  Great question man !!!!!!!

@Fattie: as I wrote at the beginning of my answer, the aerospace world is made of compromises, so it is actually normal that different answers/points of view suit the same question

It is not so much that the trailing edge is swept forward as that the leading edge is held to zero sweep.
One way to approximate an elliptical lift distribution (without twisting a wing) is to taper the wing with a taper ratio between 0.4 and 0.6.  The 540's taper ratio is about 0.46.  Enough to improve the load distribution, but without being so aggressive as to make tip stall a problem.
Often general aviation wings (solidly subsonic) will have a straight quarter-chord.  This allows them to have a straight spar and load carrythrough structure.
The 540 instead has a straight leading edge.  This is most likely to give it a striking appearance from the ground during aerobatic displays.  Maneuvers like vertical flight, 16-point rolls, and 16-point rolls during vertical flight will look better with a wing that meets the direction of flight at 90-degrees.  This will also help aerobatic judges appreciate the precision of the maneuvers being executed.

This is actually a very nice example of the compromises normally encountered in the aerospace world.
This being an aerobatic airplane, the wing should ideally deliver the same handling qualities both when flying upright and also when flying upside-down. This implies that all the standard techniques normally used to tailor the flight characteristics of the airplane cannot be used because they are normally not symmetrical when the wing is upside-down. For example, the wing should be vertically positioned in the middle, i.e. not on the bottom of the fuselage like in a jetliner (so called low-wing) nor on the top of the fuselage like in a cargo plane (high-wing). And already this single choice has a lot of consequences like the fact that the wing's structure just cut the fuselage in the middle and therefore nothing can be put there: see for example how the pilot seats behind the wing and the engine in front.
For the same reason, dihedral cannot be implemented: if you look at a jetliner's wing from the front, you'll notice that the wing goes up a bit, while in a cargo plane it goes down; dihedral is normally used to adjust the stability of the wing but, as before, in an acrobatic airplane if it would positively contribute to the stability when the airplane flies upright then it would be destabilising when flying upside-down.
Another way to optimise the aerodynamic characteristics is by using washout i.e. adjusting the local angle of incidence of each section of the wing. But, again, this method would have the same problem as before i.e. a washout optimised to fly upright would be detrimental when flying upside-down.
So in an aerobatic airplane if some in-/stability is needed, all that's left to do is sweeping the wing. In particular, sweeping the wing forward moves the lift at the tip a bit forward reducing stability, something which might be beneficial for this kind of airplane.
Note that this wing is not only swept forward but also tapered i.e. the chord at the tip is smaller than the chord at the root. This is done to optimise the spanwise lift distribution and generate less induced drag.

The primary reason for forward swept wings in aerobatic aircraft is maneuverability and controllability. Wing sweep is measured at quarter chord. Trailing edge sweep is the result of wing sweep and taper. It is not normally thought of as a design driver. Other answers deal sufficiently with taper.

Forward-swept wings also are able to maneuver at high angles of attack.  The Grumman X-29b was found to be able to maneuver and not stall up to 67 degrees angle of attack.  Good maneuverability was maintained at 45 degrees angle of attack.

why are the back of the wings of some aerobatic planes swept forward?

To optimize performance in high G loading and high angle of attack turning maneuvers.
This is an answer a pilot from 1918 might understand better than many of the higher Mach cruise-performance bred engineers of today.
Vortex formation is much more pronounced at high angles of attack, and tapering of the trailing edge is a well known technique of reducing drag, making the aircraft more responsive when power is added to accelerate$^1$.
Aerobatic aircraft also engage in many maneuvers with a high degree of side-slip, where yaw-roll coupling is undesirable.  So one takes their weight saving$^2$, elliptical span loading tapered wing and yes, indeed, sweeps it forward a bit, eliminating the yaw-roll couple$^3$.
Aerobatic pilots want pitch, yaw, and roll effects to be separate and predictable, making advanced maneuvers, such as a knife-edge, 8 point roll, or inverted flight, much easier to fly.
$^1$ and providing more (T-D) excess thrust to climb
$^2$ also very helpful for aerobatics
$^3$ "mostly upright" planes, like the Cessna 172, can also do this by increasing area underneath the CG, making maneuvers, such as the forward slip, easier to fly.  Some call this making it more "spirally unstable".

We can't see how the wing is mounted in the photo, but I assume it's probably mid-wing-- wouldn't the coupling between slip and roll be closer to zero with zero sweep?

Consider also that any coupling due to sweep reverses sign whenever the wing is negatively loaded -- unlike coupling due to actual dihedral.  I'm finding this especially aggravating when practicing slow rolling maneuvers, sustained knife edge, etc with a r.c. F-16 model with it's delta wing--I can really feel how the couple varies from significant positive when wing is + loaded, to near zero at knife edge, to significantly - when the wing is - loaded--I'd rather just have a constant (though preferably mild) coupling in one direction! (such as the case w/ my high-wing a/c with slight dihed)

@quietflyer good points.  The leading edge is straight.  (It seems to be technically "forward swept" by connecting root and tip centres with a line). A swept leading edge may have more dihedral effect, as per F-16.  And yes!, high wings are very good at reducing "dihedral effect" (in side slip), even though they have dihedralled wings, by virtue of their "keel" and wheel side areas.

One can only imagine what a biplane/turboprop Edge 540 could do! (They seem to be catching on with Vstab cable supports).

It's the easiest planform to build after a constant chord planform. Both have the spar at the 1/4 chord position along the entire wing but the plank planform has more area and mass than is optimal at the tips.
Any additional modifications to approach the theoretically ideal eliptical planform would start to require things like curved edges or spars that do not always sit at the 1/4 chord.

Swept angle refers, by definition, to the line passing through the quarter chord, so that wing is actually swept forward.

@sophit Even with that definition it still looks like zero sweep to me.

Try to connect the quarter chord point at the tip with that at the root and let me know if you get a line perpendicular to the fuselage

@sophit Sweep is most commonly defined in terms of either sweep of c/4 or LE -- but I've also seen it defined in terms of c/2.  I wouldn't be so strict that the definition of sweep is only about c/4.

These other definitions are sweep are so strange to me since the objective of sweep is to present the leading edge differently to the air. Maybe it's just more convenient in drawings to use a chordline or something.

@RobMcDonald: science is not democratic, definitions are not chosen by show of hands. At subsonic speed, swept angle is given in respect to the quarter-chord point because that's the point where lift and pitching moment act, full stop. We can discuss if at supersonic speed it's better to choose the 50% of the chord (aerodynamic center) or the leading edge (to know if the wing lies inside the Mach cone). And at transonic speed we can discuss if it's better to use the point at the maximum thickness (after which the boundary layer might detach). But at subsonic speed definition is straightforward

@sophit Good thing this is an Engineering question, not a Science one.  Definitions and conventions are arbitrary and are tools to suit a need.  You can believe that sweep is always in terms of c/4 -- but in the real world, I have observed countless times when engineers instead worked in terms of LE sweep.  The Wright Brothers were set back a year because they did not catch the difference in the 0.5 term in 0.5rhoV^2 in data they received -- that mistake led them to build their own wind tunnel and take their own data (which probably advanced their knowledge more than what was lost).

@DKNguyen There are (at least) two purposes for conventions in things like sweep angle, taper ratio, aspect ratio (and other parameters).  One is simplicity of drawing -- a design-first (whether drawing board or CAD) perspective.  The other is related to collapsing data onto a trend -- a physics-first (often observed before it is understood) perspective.  As sophit points out, there are times when different dominating physics (and your interest) will cause the data to correlate in different variables.

@RobMcDonald: the 0.5 comes out after several integrals and it is not a convention since it is mathematics. Leaving it out is a convention but a dangerous one as your example of the Wright brothers shows. That being said, at subsonic speeds the Edge 540 posses a wing which is swept forward, period

Nobody ever worked with leading edge sweep. They worked with leading edge rake. For anything other than 1/4 cord, the terminology is rake. Talking about leading edge sweep will cause aero guys to walk out of the room.

@sophit I understand where the 0.5 comes from.  My point is that using it or not was once convention.  There are multiple conventions for Cp/Cq/Ct for propellers/rotors -- depending on which side of the Atlantic you are on and whether the rotating axis points up or forward most of the time.  Choosing Sref as the area of a trapezoidal equivalent wing is just a convention.  The sweep of a B737 (or any transport with a planform break) will likely be described by the LE.  I can look at the 540 and tell you it has zero degrees of LE sweep.  Can you look at it and tell me what the sweep angle is?

The tapered forward-swept wing will optimize with a larger wingtip span (here listed as 0.46 of root) compared to an unswept wing (about 0.4) or swept wing (less than 0.4). The aeorbatic plane has large high-gain aileron controls for quick roll accelerations and precise control. The large tip is more roomy for controls and provides better roll accelerations.

@PhilSweet I have only seen rake when talking about propellers.  Lots of folks work with leading edge sweep.  And trailing edge sweep.  Look at any edge-aligned low observable aircraft.  They certainly work in terms of LE and TE sweep all the time.  I just took a flip through a DATCOM manual -- $\Lambda_{LE}$ shows up frequently there (I also saw some $\Lambda_{c/2}$)-- I guess aero guys never use DATCOM.  Has anyone ever described a delta wing in terms of $\Lambda_{c/4}$?  By far the most common convention I have seen is to always specify what x/c you're talking about when working with sweep.

@sophit I would not say that the circumference is $\pi R$ - that is wrong.  However, there are people in the world who define $\tau=2*\pi$ and would prefer that we say $D=\tau R$ and that we celebrate $\tau$ day on 6/28 https://tauday.com/.  Conventions are arbitrary.  They are meant to be useful.  Therefore, people choose whatever is useful at the time and you should always communicate your convention.

@sophit I agree that the c/4 of the Edge 540 is swept forward.  That was never in question.  However, if you wanted to communicate the sweep to me in a quantified manner -- Can you easily and precisely do that?  I can say that $\Lambda_{LE}$ is zero with pretty high precision and confidence with just a glance.  In terms of a design decision, do you think the Zivko engineers decided the wing should have a $\Lambda_{c/4}=-2.23417^\circ$?  Or do you think they decided the wing should have a $\Lambda_{LE}=0^\circ$?

@RobMcDonald I've actually already answered that in my answer, i.e. they chosen a negative c/4 sweep angle based on aerodynamic/flight dynamic aspects. And they have used the c/4 to do the maths because that is the important point at subsonic speeds, any other geometrical point is just a consequence. I seriously doubt they used the leading edge to do aerodynamic (or even structural) calculations.. p.s. I'm going to clean up a bit the comments

source: Stack Exchange

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What is this beauty, seen here after a heavy landing?
A high-wing monoplane with a curved leading edge.

It would be interesting to know whether the front downward-projecting fin was intended to skid along the ground until take-off, or what-- that would seem awkward!

@quietflyer "There was a small elevator mounted at the front of the fuselage as well as a rectangular rudder mounted underneath, which also served as a nose skid.". I bet ground handling was just swell :D

Oh! Those magnificent men in their flying machines!

It is a Blériot V. Only one was ever built and it did not fly very well. (if at all)
It was a canard configuration pusher monoplane so you are looking at it backwards. The curved part of the wing is the trailing edge, not the leading edge.

While it's aesthetically pleasing the design makes my skin crawl and I wouldn't want to fly it. It looks unstable to me, just seeing how close the wheels are together is worrying. the rudder in the front means it will have very little directional control at low speeds.

All of those (to us) extremely wierd looking designs during this 'age' of flying (very late/very early 1800/1900's... wonder how many might have gone on to be usable if they didn't simply get discarded as ideas after the first crash?

Also, looking at the above photo.. can't hep but to wonder how it was supposed to actually take off, the props look like it can't nose-up without ground striking, even with those wheels....

That is almost undoubtedly the Blériot V

The Blériot V was an early French aircraft built by Louis Blériot in 1907 and was his first monoplane. Although Blériot only achieved a couple of short flights in it, the second resulting in a crash which damaged the aircraft beyond repair, it was the first of his experimental aircraft to achieve any measure of success.

Image not subject to copyright
Here is a slightly clearer image of your "crashed" instance

Source: https://www.pbs.org/wgbh/nova/bleriot/imag-05.html

Many thanks to you all or taking the time to answer my question - much appreciated.

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Has Boeing ever tried to compete with the A380, especially now that the B747 is retired in many companies, such as Qantas?
Has there ever been a competitor that is a four-engine plane from Boeing that rivals the A380?

The premise of the question is flawed: the A380 competed unsuccessfully against the 747.
The 747 was produced for about 55 years. The A380 was in production for about one third as long, about 18 years. Over 1,500 747's were built, just over 250 A380's, so one sixth as many airframes sold. The 747 was still in production a year after the last 380 was delivered.
The market spoke, and while all large 4-engine jets are fading away in light of the power and reliability of the engines like those on the 777, A330, A350, and 787, the 747 was vastly more successful economically than the A380.

Awesome. thankyou so much for the answer. It has helped me with understanding a bit. I wanna be a pilot but i need HEAPS more background knowledge

Another thing is that the 747 is very useful as a cargo carrier due to its design while the A380 doesn't do that type of cargo.

@SMSvonderTann I actually think that is what tipped the scales. And the fact that A380 was born into a dying market.

Notably a freighter variant of the A380 was floated around but had no buyers and nothing was ever built, while the 747 layout was designed from the start to be useful as a freighter and was doing so as early as the mid '70s. Even though the reasons for changed - in the '60s it was assumed that the passenger 747 would be made obsolete by SSTs like Concorde, when it was actually made obsolete by smaller, more flexible and efficient twinjets.

No. Boeing wisely understood that the 380 was a "bridge too far", just too big for most airports. The program has been a disaster for Airbus.

Not a bad idea to throw up a challenge to the big double decker 4 engined king, but why on earth would you not impose an upper size limit on the design to be compatible with the existing infrastructure that had enabled the 747 to dominate for decades?  It can't even use the same passenger terminals, did they think airports everywhere would just build new to accommodate them?  Unbelievable strategic blunder in my opinion.  I guess the business schools needed some fresh case studies on what not to do.  (and then Bud Light says "Oh yeah?  Watch this...")

I think they really expected most airports to adapt.  I rode on one going to France on business once. Sitting over the wing, the top white painted plank was like a big trapezoid shaped skating rink. The DeHavilland Canada Dash 7 was another project based on a concept that didn't work out, use of short stubs of crossing runways to operate from at super busy airports, using the Microwave Landing System that was in dev. It was 50 seats, 4 PT6s, optimized for STOL, but only about 107 were sold. The massively successful Dash 8 was basically a do-over, abandoning STOL for efficiency.

Which makes it all the more surprising that A380s are more common in Europe while Boeings dominate the US market, given that Europe is just generally more crowded, and American airports have more physical room to grow to accommodate larger planes.  Obviously where the planes are built factors into it, but you'd think there'd be a bigger market for larger planes in the US...

I would say airports in Europe went a lot farther in making changes to accommodate the 380, for obvious team reasons. The biggest one IIRC is simply the weight of the thing, requiring new taxiway and ramp foundations. Perhaps if the order book had grown to several hundred units, other airports may have been more willing to make the improvements required.

@RalphBolton The 380 is more or less a failure of the marketing and sales engineering team that clearly miscalculated the market. Not sure what the breakeven quantity was, probably 300+, but they are short of that. They probably built enough to mitigate most of the loss from brining it to market, so it's not a company killer. The product support organizations of OEMs charge airlines for services on a/c not in warranty, and do outrageous markups on spares (100s of percent), so eventually the out of warranty fleet becomes an income cash cow, further mitigating the financial hit.

@DarrelHoffman I wouldn't really say that A380s are very common in Europe, either. Air France retired all of theirs. Lufthansa only recently decided to bring theirs back for a few years because they weren't getting new aircraft delivers from either Boeing or Airbus as soon as they had hoped. BA will probably keep theirs around for a bit longer because of Heathrow's slot limits, but even they don't have very many of them. The market - in North America, Europe, and pretty much every else except Dubai - has spoken loudly that twins like the 787, 777, A330, and A350 are the way to go.

@DarrelHoffman I would also note that Air France's A380s were less than 10 years old when they were retired. While a lot of 747s have also recently been retired, those were mostly 20-30 years old, not 10. Air France's youngest A380s was less than 6 years old when it was retired.

Yeah that says a lot about an airplane's place in the world when units are scrapped decades before it hits its structural cycle limits. It also suggests that there are premature fatigue issues not covered by warranty that are making the cost to keep them going not worth it.

Boeing did the same market studies that Airbus did and came up with quite different conclusions.
Airbus concluded there was a massive market for very large aircraft operated on trunk routes to eventually replace existing 747s. They designed the A380.
Boeing concluded that the future market was for a larger number of smaller aircraft with shorter turnaround times, and designed the 787 (originally they tried for the Sonic Cruiser, adding increased speed into the mix as well, which idea they couldn't get to work).
So no, Boeing didn't try to compete with the A380 because it wasn't in their vision for the future of civil aviation.

Actually, all studies came to similar conclusions, but the French side of the consortium never accepted a No. From decades of trying to sell smaller airplanes with the competition subsidized by 747 profits, they had grown an irrational desire to turn the tables and do to Boeing what Boeing had done to Airbus.

@PeterKämpf: can you elaborate an answer from your comment? It's going to be interesting

I think Airbus felt they needed to prove they could build something as good as the "queen of the skies".....that didn't work so well.

@Anilv technology wise the A380 was brilliant, it just was the wrong plane at the wrong time for the economy as it was introduced not too long before the air travel market worldwide flattened out and then went into a nosedive. While it was in production sales outperformed those of the 747, which also was discontinued for that same reason.

Actually Boeing and Airbus cooperated for a couple of years at the beginning of the project:

In January 1993, Boeing and several companies in the Airbus consortium started a joint feasibility study of a Very Large Commercial Transport (VLCT), aiming to form a partnership to share the limited market.
In June 1994, Airbus announced its plan to develop its own very large airliner, designated as A3XX. Airbus considered several designs, including an unusual side-by-side combination of two fuselages from its A340, the largest Airbus jet at the time. The A3XX was pitted against the VLCT study and Boeing's own New Large Aircraft successor to the 747. In July 1995, the joint study with Boeing was abandoned, as Boeing's interest had declined due to analysis that such a product was unlikely to cover the projected $15 billion development cost.

Boeing actually knew about the A380 project for some time. Boeing, however, chose to develop the 787 Dreamliner and 737-MAX instead. Boeing figured the market was headed away from the hub-and-spoke model that the 747 had dominated for decades. While there are still airlines that heavily rely on that model, they are getting rarer. (2013 article)

The airline's stance reflects the broader aviation picture. The purchase of an A380 or 787 is far less a decision between manufacturers than a question of competing visions of the economics and future of air travel. Airlines carrying high volumes of passengers on major routes favour the A380, and Emirates - by far the largest customer - has refitted its Dubai hub to service its fleet, which is set to reach 140 planes. Five depart Heathrow for Dubai daily. At crowded airports where slots are at a premium, putting more customers on each plane taking off can make real sense.
But if the A380 is, as an Airbus spokesman put it, a "congestion buster", the 787 is better known as a "hub buster" – one that rewrites traditional models of funnelling connecting passengers onto the jumbos that make long-haul flying viable. With fewer seats, its fuel efficiency and range are enabling the likes of a direct Heathrow-Austin connection – BA's next new route for 2014 – even with less passenger demand than established routes.

One reason for that is that in the days of the 747's launch, very few lesser cities had commercial airports and air travel was expensive. So if you wanted to travel to Europe, you'd fly to JFK in New York and connect in a wide body to another hub in Europe. Nowadays, you can get direct flights from many places and skip the hubs entirely. The airlines fly smaller jets to accommodate the demand. This is what contributed heavily to the doom of the A380 line

Is it really true that few smaller cities had commercial airports at the time of the 747's launch? Or rather that there was neither the market nor the aircraft (nor facilities) to viably operate long-haul flights from those cities? At least where I live (SE U.S.,) I know of lots of small cities near where I live that had commercial air service in the 50s/60s that don't today. A lot of those were served by piston props and lost air service during the jet age (probably in large part also due to the development of the Interstate Highway System enabling quick land access to larger airports.)

@reirab I guess it depends where the airports were. Not many were "international" back in the day outside of major airports

@reirab international service requires a customs office, which I think would be a much larger burden for small airports.

@MarkRansom That's mostly true (ignoring the Preclearance program,) but I was just responding to the part of the answer that says, "One reason for that is that in the days of the 747's launch, very few lesser cities had commercial airports and air travel was expensive." Commercial air service doesn't have to be international lots of small airports had commercial domestic feeder flights to larger airports back then before the Interstates dramatically cut down the land travel time to the larger airports from smaller cities. But, of course, those rarely had international service.


text:
Why does the faster-moving air over the static port not result in a lower static pressure?
I understand the concept that the static port is measuring "static" pressure, meaning the pressure the air is exerting on its surroundings.  However, there is also Bernoulli's principle, which, put simply, states that as the velocity of air increases, the pressure it exerts on its surroundings decreases.  We see this in effect in venturis, of course, but it seems to me that Bernoulli's principle would also imply that the pressure observed from the static port would similarly decrease as the aircraft accelerates.  Obviously this doesn't happen however, since the altimeter is unaffected by acceleration.
Thus my question: why does the faster-moving air over the static port not lower the pressure it exerts?
Here is a video explanation of Bernoulli's principle being used in pitot-static systems, which seems to suggest the static port would indeed observe a pressure decrease (I've labeled the part I think the narrator is using as the static port):

Why do you think the flow is accelerated over the static port compared to upstream?

There is a small effect but the designers try to minimize it when they place the ports on the aircraft. That’s why the altimeter reads high and there is a momentary jump in the VSI when you open the alternate static port inside the aircraft.

Related, probably not a duplicate: Does the pressure at the static ports drop as the aircraft's speed increases?

Bernoulli's principle would also imply that the pressure observed from the static port would similarly decrease as the aircraft accelerates.

It's not that simple. Aircraft are complicated shapes. The fuselage is composed of all sorts of angles of attack, things sticking out into the airflow, and the pressure distribution of air across it is very uneven, just like that of a wing is. Take a look at this diagram from an FAA mechanics publication.
There are zones (like points 2,3, and 5 in the diagram) where the static pressure deviation is zero. This is where the engineers put the static ports.
Another way to think about this is that you're right that the airflow over the static ports should make the pressure lower--- but the question is: lower than what? The answer is: lower than the airflow's stagnation pressure, when the outside airflow is at rest (relative to the aircraft). Which happens at the nosecone, or the leading edge of the wing... or at the pitot tube. It's lower than that by the same amount that the pitot pressure is higher than ambient, making the pressure at the static port exactly ambient outside pressure. Which should make sense, because in the reference frame of the air, that static air isn't doing anything but sitting around waiting for an airplane to come by.
The Bernoulli effect does, however, have an overall average result: the cabin pressure in the airplane is lower than static, because the angle of attack of the various surfaces of the fuselage generates suction, pulling a small amount of air out of the cabin, just as it does for the wing if there are little holes in the wing. Which is why you get the little blip when you pull the Alternate Static open.

However, there is also Bernoulli's principle, which, put simply, states that as the velocity of air increases, the pressure it exerts on its surroundings decreases.

I think that's accurate.
So let's suppose you're flying at 120 knots. The air ahead of the aircraft is moving at 120 knots (in the aircraft's frame of reference). The air immediately outside the static port is also moving at 120 knots. The air behind the aircraft is, of course, also moving at 120 knots.
Since the speed of the air is the same in all three locations, according to Bernoulli's principle, the pressure should be the same in all three locations, too.
So, we've established that the air pressure immediately outside the static port is about the same as the air pressure several feet away from the aircraft. Can we conclude that the air pressure inside the static port is also the same? Bernoulli's principle doesn't tell us the answer. The main reason is that Bernoulli's principle only applies along a streamline, and the air outside and inside a static port are not on the same streamline.
But in any case, Bernoulli's principle doesn't give us any reason to think that the air pressure in a static port should be lower than in the surrounding air.

As pointed out by JScarry, the position and shape of the static port opening on the airframe are carefully chosen to minimize any ram air or suction effect and thereby sense the static pressure as accurately as possible.
In homebuilts, the static port location has to be determined by experiment, and if your experiments are sloppy, you'll find it possible to fly 250 MPH on a 65 HP engine (I'm exaggerating a bit here; I knew someone who built a kitplane with a homebrew static port and attributed its impossibly good top speed to his superior construction technique ;-))


text:
What operational differences were there in WWII for constant speed vs. fixed pitch propeller warbirds?
I have read about the operational differences between constant speed and fixed pitch propellers.
Being a World War II buff, I was reminded of reading once about both principles being used in period fighter planes, with the Germans preferring one and the British preferring the other, but that's about all that I can recall. (That might have been a solid 20 years since...)
So, my question is:
How would the above-mentioned "operational differences" apply to WWII-period warbirds specifically, and does anyone have links or pointers to relevant reading material?
I think a period warbird has a quite different set of requirements on its performance and handling characteristics, which is why I think this separate question is warranted.
I'm not so much interested in the fine technical details (I don't want to build / maintain / model one of those planes based on this information), but rather striving for a better understanding of the relative performance characteristics of those (IMHO) most beautiful planes of all time.

Didn't the Brits still have old biplanes when war broke out? I bet those had fixed pitch propellors.

When war broke out, almost all high-performance military planes on all sides had variable-pitch propellers. Not necessarily constant-speed types, but adjustable nontheless. There was no difference between German and British planes.
If there was a difference it was the use of manually-adjustable propeller pitch, which was widely used in German airplanes, versus constant-speed propellers, which found more use in British airplanes. However, both sides had both types of propellers in their fleet, so it is hard to make a generalization.
Operationally, the manual adjustment gives the pilot more control, but increases workload because the pitch has to be adjusted when flight speed changes. This was less burdensome in bombers, but in fighter aircraft a manual adjustment would keep the pilot busy during dogfights.
Early types of the aircraft involved did indeed use fixed-pitch propellers, like early versions of the Me-109 A and B or the Hawker Hurricane Mk.I. By 1939, both types had long since converted to variable-pitch propellers.
Older airplanes with fixed-pitch propellers were still used for training or liaison, but not near the front lines. Exceptions are aircraft like the Polikarpov Po-2 which was used for night attacks until the Korean war. It had such a limited speed range that a variable-pitch propeller would not had made sense.

Douglas Bader crashed a Spitfire in the spring of 1940 while attempting take-off, having inadvertently left the propeller pitch at the coarse setting (he suffered only slight injuries, though his prosthetic legs were crushed.)

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Can jet engine ingest (suck in) concrete from runway?
In the question Is there any emergency situation in which jet engines would not be shut down before passenger evacuation of a transport aircraft comment says:

At full engine power, those vortices are quite capable of lifting something the size of a 1-foot cube of concrete from the ground into the engine!

Incredible! Did it really happened? I guess it did not ended up well for the engine. Any links/images?
I found this:

Can a human get sucked into a jet engine? - but concrete is denser than water (human body), so it would be harder to suck in
Can jet airplanes operate on 'rough' airfields? - mentions gravel, not concrete tiles.

Concrete is 2.4x as dense as water, so 1 foot of concrete is about 0.7 meters of water, which is like 0.07atm. Yeah if you managed to suck a vacuum above the entire run way you can lift the entire run way easily, theoretically.

Is a one foot cube of balsa wood "the size of a 1-foot cube of concrete"?

I hope very few runways have loose chunks of concrete sitting around.  Maybe after a major earthquake, or a bombing run...

@DJohnM -- yes, both are one cubic foot in size

Small, loose pieces, it sure could.  But those are small flakes which would fit in your hands.  Large chunks, it’s doubtful that the suction could lift them to ingest them off the runway.  Now there’s a chance such a piece could get kicked up by the nosewheel of an airplane during a ground roll and thrown into the intake of an engine.  Airports generally have surface crews which periodically do FOD sweeps of the runways and taxiways looking for debris like that.

Basically, atmospheric pressure is 14.7 psi and a jet engine functions as a vacuum. Given somebody else's postulate that a cubic foot of concrete weighs 150 pound per cubic foot and that an absolute vacuum exerts 14.7 * 122 == 2,116.8 pounds of pressure per cubic foot, it will blend... and fly... if it gets close enough to the jet intake.
A jet engine won't exert a full vacuum, but even a household vacuum cleaner tends to exert about 3psi, which if it scaled up to jet engine intake size would also lift said concrete block.

If anybody can share the suction / distance formula for say the GE-90 engine, I'd appreciate it. 2 million CF/M consumed in a 128 inch diameter.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Is there an equation which allow us to perfectly match a helix propeller and an engine?
Is there an equation which allow us to perfectly match a helix propeller and an engine? I'm looking for an equation that allow me to correctly dimension an helix propeller for my engine. I mean that allow me to maximize efficiency and thrust, calculate the optimal number of blades, the optimal number of rpm, and the maximum rpm of my helix propeller given a certain engine power, etc.
Should I ask this question on the physics division of this website?

Did you try Mark Drela's XROTOR? I have difficulty with your term "helix", but that software should do what you ask if your blade loading is not too high.
From the linked page:
XROTOR is an interactive program for the design and analysis of ducted and free-tip propellers and windmills.
It consists of a collection of menu-driven routines which perform various useful functions such as:

Design of minimum induced loss rotor (propeller or windmill)
Prompted input of an arbitrary rotor geometry
Interactive modification of a rotor geometry
Twist optimization of an arbitrary rotor for minimum induced loss
Analysis of a rotor with a wealth of choices of operating parameters
Incoming slipstream effects (from an upstream propeller, viscous wake...)
Multi-point parameter display
Structural analysis and corrections for twist under load
Acoustic analysis with dB noise footprint predictions
Interpolation of geometry to radii of interest
Plotting of geometry, aerodynamic parameters, and performance maps
...


text:
May two airplanes wait on the same runway at the same time?
In a normal situation, the controller doesn't authorize aircraft to simultaneously line up and wait on the same runway.
However, if two aircraft call the tower ready for departure, one at the full length of a runway and another at an intersection, can these two aircraft be allowed to line up and wait on the same runway at the same time? (like in the picture)
I referred to FAA Order 7110.65AA 3-9-4. Does the 'intersection' mean the departure position of aircraft preparing for an intersection departure?

f. An aircraft may be authorized to line up and wait
at an intersection between sunset and sunrise under
the following conditions:

The procedure must be approved by the
appropriate Service Area Director of Air Traffic
Operations.
The procedure must be contained in a facility
directive.
The runway must be used as a departure−only
runway.
Only one aircraft at a time is permitted to line
up and wait on the same runway.
Document on FAA Form 7230−4, Daily
Record of Facility Operation, the following: “LUAW
at INT of RWY (number) and TWY (name) IN
EFFECT” when using runway as a departure−only
runway. “LUAW at INT of RWY (number) and TWY
(name) SUSPENDED” when runway is not used as
a departure−only runway.

g. Do not authorize an aircraft to line up and wait
at anytime when the intersection is not visible from
the tower.
h. Do not authorize aircraft to simultaneously line
up and wait on the same runway, between sunrise and
sunset, unless the local assist/local monitor position
is staffed.

Note that the current version of the 7110.65 is AA CHG 1, and AA CHG 2 will be effective in two days (3/21/2024). The current version is always available in HTML format at https://www.faa.gov/air_traffic/publications/atpubs/atc_html/ and the persistent document-control page is https://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.current/documentnumber/7110.65

Yes, this is permitted. "Intersection" refers to the position on the runway of an aircraft which will not use full length for their departure.
Per the .65, there are restrictions to this procedure:

It is not permitted at night (specifically, between sunset and sunrise) (3–9–4f4), and
The intersection must be visible from the tower (3–9–4g, the same as any intersection LUAW), and
The local assist/local monitor position must be staffed (3–9–4h).

During the daytime, with the intersection visible from the tower, and with the local assist/local monitor position staffed, this is a legal procedure.

If this is correct, then what does f4  mean, or why does it not apply?

@MikeB: Subpara f is the list of requirements/procedures for using LUAW at an intersection at night ("between sunset and sunrise"). If you can't comply with all of f1 through f5 then you can't use intersection-LUAW at night. But during the day subpara f is moot.


text:
Is it permissible to walk along a taxiway at an uncontrolled airport to reach airport facilities?
I just got my PPL and am planning to take a short $300 hamburger trip tomorrow to a nearby uncontrolled field. Here's its taxiway diagram:

I called the airport this morning to ask where transient parking is located, and they told me it's along the east side of that taxiway loop north of the runway. The diner is located on the western side of the loop, near the gas pumps.
Seemingly the only way of getting there is walking along the taxiway (or cutting through the grass).
All my training was done out of a busy class D, so my experience has always involved walking onto the ramp from my flight school, and then getting taxi clearance before entering the movement area. I've never gotten out of my plane at an uncontrolled airport before, except to get fuel. Walking along a taxiway doesn't seem right, but I'm not sure what else one would do here. Is that just what one does at uncontrolled fields? (It's funny how much training you receive to get a PPL, and how little of it focuses on day-to-day operations at unfamiliar airports and FBO facilities.)

FHR? Looking at a satellite view, it looks like you'd either walk along the northernmost taxiway that doesn't intersect with the runway, or depending on the height of the field and your seasonal allergies, just walk across the field that is under the final for 16. If it's busy, call the FBO or restaurant and ask about the local procedure. And you're right, the practical things like this aren't covered!

Yup, FHR it is. And walking along the north taxiway is what I assumed. Hopefully nobody will yell at us!

Why do we drive on a parkway and park on a driveway?  You can run on a walkway, but don't try to walk on a runway!

@MarkRansom I've walked (and ran) on runways several times, including at KBNA and even KATL. :) Pretty cool experience, actually. I recommend it if you get a chance.

@MarkRansom And have you ever seen a taxicab on a taxiway?  I haven't.

@WayneConrad Sort of, if you count these.

Why don't you just ask to park next to the diner?

Where you can and can't go on an uncontrolled airport is up to the owner, or the manager, beyond common sense things like not walking on the active runway.
In any case, if I was told to park on the east side of the taxiway box at the top, I'd probably walk around the north part of the loop, or if the grass was cut short, might cut across the grass to the north, staying well clear of the end of the runway. Look around for any signs posted on where to park and where to walk. If none, just use common sense.
If you wander into a bad place and get scolded, well, we've all been through that some time or other. I had an airport manager walking toward my plane, as I was getting out of it to tie it down, with steam coming out of his ears.  I knew instinctively he was pissed at me taxiing too fast, because, well, I was. As soon as he arrived and was about to open fire, I apologized and assured him I'd never do it again.  The steam was released, he said, "ok, good enough." and left.

Erhmagherd, just how fast were you taxiing??? I don't think I've ever seen someone taxi so fast I thought it was notable.

Prolly about 20-25 mph.  It was through a large ramp area with parked AC, not on a taxiway itself

A non-towered airport has no movement area, despite any pavement markings or signs you may see. Ditto for a towered airport when the tower is closed.
It’s quite common at small airports for taxiways to double as roads for cars to get to and from hangars, and pedestrians can use them as well. Just keep your eyes and ears open, and of course give way to any actual aircraft, and you’ll be fine.
Technically runways fall into the same category, and I’ve seen a few very small airports where cars must drive on the runway, but for a pedestrian  this is ridiculously unsafe and should be avoided if at all possible.

I really want to clarify something that has been left far too vague in other responses.  From a federal regulation (FAR) standpoint, there may be no legal prohibition from walking in non-towered movement areas.  But that is only FARs and airports are not owned by the federal government.
In my state you are not free to walk about or drive about the airport in non-designated areas without the express permission of the airport operator, irrespective of being towered or not.  For instance, in my state it is a misdemeanor to drive a motor vehicle anywhere on airport property not specifically designated for motor vehicles, without the express permission of the airport operator.  This includes both state-owned airports, and any municipal/private airfield that is state licensed.
I am not saying you'll get in trouble, you almost certainly won't if you are acting in a responsible manner.  And being a pilot you would be given enormous latitude.  But no blanket statement about what is legal at all airports should ever be made, or trusted.  Non-flight activity on the airport grounds is entirely the domain of state, local, and municipal codes, or the rules of a privately owned airport.
"I've done it a few times and it was cool" does not constitute something being legal.

At an uncontrolled airfield , you may walk but with a reflector jacket and staying away from taxiway.
I've done this before as I've completed my training at uncontrolled airfield.


text:
What is this flying boat and launch tower?
What is this structure and aircraft? It is Real Photograph number 188.

What is "Real Photograph"? Is it actually a proper noun? What does it refer to?

These were photographs issued by the Real Photographs Company of Liverpool, all with their number printed in the negative, and usually with their address details printed or stamped on the reverse.

I'm almost certain I've seen this in a blooper reel. It falls off the end and then we get funny music

Judging by the “FB” on the tail, the aircraft is most probably a Franco-British Aviation FBA 17 designed by Louis Schrek.
More info here: https://www.sas1946.com/main/index.php/topic,54251.msg590104.html#msg590104

Possibly a more valid aircraft ID than mine.  Fin-rudder shape don't seem quite right, but fuselage is better.

@ZeissIkon - Mike’s first picture looks like it could be that exact airplane right down to the color scheme on the tail. Vstab shape looks like exact match to me.

I'm wi8th @Jim but the white vertical stripe in the photo in the Q does funny things to the apparent shape

That looks like a fixed test article representing an early version of the catapults used to launch flying boats and float planes (like the Kingfisher) from battleships before carriers were integrated into the fleets.
See this article for (one of) the last iterations of this kind of catapult.
Aircraft launched this way were recovered by landing alongside and winching back aboard.  Once the jet era began, no competitive fighter aircraft could be launched with this small a catapult (nor did any exist with floats or as flying boats -- there were a couple such designs, but they went nowhere), and aircraft carriers had much stronger catapults mounted in the flight deck (a practice that continues to the present), obsoleting this launching method and indeed launching fixed-wing aircraft from non-carrier ships until VTOL jets became common.
The aircraft on the cradle looks very much like an (Aeromarine 40) (I now believe this is correctly the FBA 17 as given in the other answer).  Correct tail shape, wing type, extended trailing edge ailerons, and inline or V engine.  That would date this photo after the Armstice, likely during the early 1920s.
Note that the aircraft shown on the catapult is essentially a late WWI design -- fabric and wires on a wood or steel tube frame, the hull a little sturdier than the wings in terms of covering.  Even if designed to be armed, aircraft from that period always look fragile compared to even the biplane fighters of the 1930s.

Many thanks to all of you for your time in answering this. Much appreciated.

So, it's a fighter plane?  Doesn't seem to have any weapons on it, nor does it look big enough to carry any - was it just used for aerial recon or something?

I believe (whichever model it was) it was being used mainly to test the catapult.  This was between wars, but the design is very much like late WWI aircraft, which universally looked too frail (to the modern eye) to carry guns or bombs.

I think, @ZeissIkon, that you could stop at "which universally looked too frail". Period. End of story. It's always amazing that those pieces of balsa wood & tissue paper managed to fly! ;)

@FreeMan Can't argue much with that.

@DarrelHoffman It is most definitely not a fighter plane. Battleship placed aircraft were used for search mission, and directing fire from the battleship. They had some self defense capabilities against enemy aircraft, but if encountering enemy aircraft their best defense was to find a cloud to hide in.

Regarding the part that states "before carriers were integrated into the fleets", carrier aircraft did not displace the battleship mounted search aircraft in all fleets. For example, the Japanese maintained them through WW2, and they proved very helpful for battleships operating separate from carriers. (One might even argue that they enabled such operations in the presence of air power.)

@AkiKorhonen It would probably be more correct to say "before the obsolescence of battleships and cruisers".  But by the time the jet era was well established, of course, non-carrier ships had started to carry helicopters.

@ZeissIkon Agreed.


text:
What physical and mental attributes do I need to become a pilot?
I want to be a pilot (civil aviation), but I'm afraid that my body composition and field of study might not fit with aviation. What are the physical requirements and academic/mental prerequisites to become a private pilot?
For instance, I have a masters degree in computer engineering and am skinny (50Kg, 1.72m and 24age). Could this be a problem?

I think a better question is why do you think that the characteristics you've listed suggest you could not be a pilot?

You don't need physical strength to be a pilot. Some fly even without a hand! You only must not have any disease that could cause sudden disabling condition (e.g. epilepsy, arrythmia, strong diabetes and such).

or be taking any psychoactive medication for mental conditions. I was disqualified from getting my PPL (in Australia) because I have ADHD and am taking Dexamphetamine.

Well you're going to want to bulk up to around 80 or 90kg of pure muscle so that you can fight with the controls, and thats just for takeoffs. To land you'll need to proficient either kung-fu if you're flying in the northern hemisphere, or krav maga if you're flying in the southern. On top of that you will probably want to get laser eyes installed. Just kidding, pilots are just normal people who are in better than average health

172cm shouldn't be a problem IMO (I am the same size as you, but 63 kg). In fact it's probably the sweet spot size for reaching for cockpit controls and ease of sitting in the cockpit!

Shhhhhh, here is the biggest secret of aviation: It's actually quite easy to become a pilot.  You can actually get your private certificate before you are allowed to drive!
The FAA has a nice page that tells you what is required to become a private pilot.  When most people think of piloting small general aviation aircraft, they are thinking about the Private Pilot certificate.  Part 141 is the most common route for that.  The hardest part is being able to pass the FAA physical, but keep in mind that as a private (or even recreational) pilot, you don't need to get a Class I, just a Class III.
To become an airline (ATP) or military pilot does require a great deal more work and training, but I think that may be beyond the scope of your question.
The best advice is to go to the local airfield or FBO and find a flight school.  Good luck.

Judging by his use of the metric system, I would say the FAA page would not apply.

What are the physical requirements

My (future) mother-in-law saw me stepping out of the airplane and said to her daughter "how can such a little guy fly such a big airplane*?" In a word, hydraulics.
Ultimately you must be able to move the control surfaces through their normal range of motion, perform emergency procedures, and safely control the aircraft. There is no rule that says you're not allowed to slide down the seat a couple inches to get full rudder deflection because your left engine just quit. I personally know a pilot who flew with a very thick book behind his back. No, I'm not kidding.

99' 6'' long, 130' wingspan, 156,000 lbs max GW

Based on the vital statistics related to your physique that you have provided you can very easily apply for a Pilot's licence . Some of the important information related to how one can become a Pilot are as follows :
(1) You do not need to go to an Aviation College and get an Aviation degree to become a pilot. Some regional US airlines prefer an associates degree or at least two years of college experience. Major airlines typically require a bachelors degree, but it can be in any field of study, not just aviation .
(2)As long as your vision can be corrected to 20/20 with glasses or contacts, you will be eligible for a 1st Class FAA Medical Certificate, which makes you eligible to fly as a civilian professional pilot .
(3) The cost of flight school is relatively expensive and most students will need to finance some, if not all, of the flight training cost . Airlines will perform a credit check as a standard step in their background check process .
(4) You can hold a commercial pilot certificate as young as 18 years old .
The detailed information can be found here
http://www.airaffair.com/Library/start-airplanes.html
For a Synopsis of Medical Standards prescribed by FAA , you may choose to visit this site
http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/standards/

Thank you all. I would be glad if you tell me some pointers to free scholarship providers for financing my aviation training. I don't care what ever airlines would the provider be.

How is a credit check in any way relevant to being a pilot?

There's no prohibition on computer engineers being pilots.
So long as you can operate the controls of your aircraft and see out clearly, there's no reason why height, weight or age should be an obstacle.
A 16 year-old schoolgirl can be a pilot.
and trainees are as young as 7. In some places at age 5, you can be a pilot of sorts. It's a bit harder to get a job flying jumbo jets commercially, but there are 20-year olds doing this
Obviously you have to put in the time and effort and have a minimum of
health and mental competence.

I can offer you some advice as I had the same dilemma before I took my first flight.  If you ignore the physical requirements, of which there are only a few restrictions - basically they want to know if you have any condition that will allow you to become incapacitated - for example, epilepsy; and that you are in a fit mental state - the other things you might want to keep in mind:

You need to have a good command of English; as this is the language of aviation. Perhaps not a requirement if you are a native English speaker - but you need to be able to understand the instructions from traffic control quickly and relay them back. Don't be afraid to tell them you are a student and they (might) go slow on you.
You need to be able to strictly memorize and follow directions. I know this sounds like one of those things that you would need on any job; but being a pilot one small goof in the checklist can end up with a disaster.  If you are a glutton for procedures and steps, man is this the place for you!
You can't daydream. As my instructor at the time said "you need to be ahead of the plane", meaning if you are already anticipating what the plane will do, if something sudden comes up you can manage.  It is insane how many things you have to keep track of especially if you are in a trainer aircraft like a 172 that doesn't have a full electronic cockpit or autopilot as in most commercial aircraft.

If you want to be a recreational pilot then that's all there is. Once you get the basic hang of what goes on in a flight, then all you have to do is keep up your hours and get type rated for the kind of aircraft you want to fly (dual engine, turboprop, jet, etc.)
Go for it!

You definitely are big enough.  My daughter did her first flying lesson at 11 or so.  We had to pull the seat way up and have her sit on a cushion.  She was well under 5 feet and 100 pounds at the time.  She did just fine.
As far as the academic/mental prerequisites a calm demeanor is good. As is thinking ahead, plan, not react. Just remember the most important thing is the next two things.
The other thing to remember is the plane does not care what degrees you had, what university you went to, etc.  So don't think that since you have a graduate degree you have a leg up on someone that is a high school drop out.  I have had this reinforced to me several times.  I have several degrees (physics, math, computer science) and all of that learning meant zero if I don't practice the basic over and over and exercise good airmanship.
Best of luck with your flight training, and have fun.


text:
How should the Swiss international airlines flight 850 METAR reports be interpreted?
From the Wikipedia page on the Swiss International Airlines Flight 850 crash investigation, it was stated that the initial METAR did not reflect the situation and the METAR less than an hour (a moment before the approach was started) was drastically different.
Initial METAR:

EDDT 04001KT CAVOK 30/17 Q1002 A2959 0998 2947 NOSIG.

Later:

EDDT VRB01KT 9999 FEW040CB SCT120 BKN260 29/17 Q1002 A2959 0998 2947 TEMPO 27025G55KT 2000 +TSRA BKN009 BKN015CB COMMENTS: OCNL LTNG AND CB SW OF STN.

I'm not very familiar with these reports, or how they are generated. From some research it sounds like the second report is much more serious, however I'm having trouble understanding a few things:

VRB01KT

This seems to suggest variable visible range, but I'm not sure what the 01KT means.

Can someone clarify?

The later report first mentions scattered cumulonimbus clouds, but then says the coverage is up to broken.

Why are there multiple mentions of the same types of clouds?
Are they talking about different height/direction?

The Wikipedia article seems to suggest that there was a massive storm moving rapidly into the area. My understanding is that NOSIG means the weather is not expected to significantly change in the next two hours.

What would cause the initial report to include NOSIG?
Given how much worse the weather seems to be in the later report, why would it take the station almost an hour to file a new report?
Why wouldn't they file a new report as soon as it seemed like the weather was degrading?

VRB01KT is about the wind - "Variable at 1 knot"

You've got 6 questions in there, though 2 of them are based on the incorrect assumption in the first question (as addressed by @JonStory), so that really leaves you with the last 3...

You can decode METAR data online if you wish, see this answer: What is the meaning of this information provided by Air Traffic Control?

The metars are incomplete- they lack the time stamp right after the icao location indicator.

Can someone clarify?

I can try to clarify the METAR report:
From the Wikipedia source link on METAR:

EDDT:  METAR for Tegel Airport
VRB01KT: Wind variable at 1 knot (1.9 km/h)
9999: visibility in excess of 10 kilometres (5.4 nmi)
FEW040CB: few clouds at 4000 ft. including cumulonimbus
SCT120:  scattered clouds at 12000 ft
BKN260:  broken clouds at 26000 ft
29/17: temperature 29 degrees Celsius, dew point 17 degrees Celsius
Q1002: current altimeter setting (in QNH) is 1002 hPa
A2959 0998 2947: current altimeter setting 29.59 in.Hg, falling to 998 HPa, 29.47 in.Hg.
TEMPO: Temporarily

27025G55KT: Temporarily winds from 270° at 25 knots (46 km/h), gusting to 55 knots (102 km/h)
2000 +TSRA: visibility 2000 meters (1.1 nmi)
+TSRA: heavy thunderstorm and rain
BKN009: broken clouds at 900 ft
BKN015CB: broken clouds at 1500 ft including cumulonimbus

COMMENTS: OCNL LTNG AND CB SW OF STN: Occasional lightning and cumulonimbus clouds south west of the station

Why are there multiple mentions of the same types of clouds?

The TEMPO group is used for any conditions in wind, visibility, weather, or sky condition which are expected to last for generally less than an hour at a time (occasional), and are expected to occur during less than half the time period.

Are they talking about different height/direction?

The Sky Condition (i.e.:FEW040CB SCT120 BKN260 ) reports the sky coverage and is given for different height, the following three-digit height is given in hundreds of feet.
For further clarification of METAR convention I find this useful!

My understanding is that NOSIG means the weather is not expected to significantly change in the next two hours.

Correct, NOSIG stands for NO SIGnificant change, doesn't mean that the weather will not change!

This is an excellent translation of the METAR, but it doesn't address the other questions. Of course, it may be that the only realistic answer is "because weather"...

Your cloud bases are out by a factor of 10: FEW040 is few at 4000, not 400, etc.

Also, I just noticed that you don't offer a translation for Q1002. That's the barometric pressure, isn't it?

Thank you @FreeMan, well spotted, and correct, I added it!

Thanks @Pondlife, you are right, they were all off! I corrected it!

+TSRA is Thunderstorm with heavy rain.  (The "+" modifies the RA, never the TS... a TS is a TS, but the RA can be light, moderate, or heavy.)

NOSIG stands for no significant change, but in practice I've seen it in each in every metar unless it had a BCMG, even if the weather was significantly variable and there was a new SPECI coming out every couple of minutes.

0998 stands for qfe in hpa and 2947 stands for qfe in inches( or whatever exotic system use the Americans ;) )

Also - tempo marks the beginning of the short term prognosis (next two hours) of the weather at the airport, so you should add something like "for the next two hours ..."


text:
Is airframe heating a concern at subsonic speeds?
It is a well-established fact that airframe and skin heating due to air friction is a significant concern with supersonic aircraft.
However, below Mach 1 (i.e. typical commercial aircraft flights at normal cruising altitudes), is there any sort of measurable heating to the airframe/skin that can be observed or needs to be dealt with in some manner?

Hello Scott, welcome to Aviation.SE!

Yes, aerodynamic heating is observed even at speeds that are well below Mach 1.
The practical application of this heating is the difference between Total Air Temperature, TAT, and Static Air Temperature, or SAT.  In essence, SAT is the actual temperature of the air, while TAT is the temperature that the moving aircraft "feels" due to aerodynamic heating.  When climbing and descending at low and medium altitudes, ice can accumulate on an aircraft when the TAT gets close to or below freezing. A common rule is to turn engine anti-ice protection on when in visible moisture (rain, snow, cloud, etc) once the TAT is below +10 degrees Celsius, since some cooling may occur in the inlet and you want to have a margin of error.
It is common to be descending at, say, 300 knots, in IMC (i.e. in clouds) and observe a TAT above +10, then when slowing down to be below 250 KIAS below 10,000', the temperature drops several degrees so that anti-ice is now required -- the difference being the additional heating that is lost as the aircraft slows down from 300 knots to 250 knots.
At high altitudes, roughly 30,000' or slightly above, where the TAT is always well below zero (although still above the SAT), a different limit is noted: below -40 degrees Celsius, the air itself is too cold to have enough moisture to cause icing, so in climb & cruise below -40, the anti-ice can be turned off.  (In descent in IMC, the anti-ice is turned on regardless of the SAT, because descending into air that CAN support icing without your ice protection turned on could make your day far too exciting -- in a bad way!)
Also, at very high altitudes on a cold day, it's possible to have temperatures that are low enough that the freezing point of your jet fuel can be a concern.  Again, this is a matter of TAT, because that's what the structure of the aircraft feels.  One solution if the fuel tank temperature begins to approach the freezing point it to increase speed, which will raise the TAT somewhat.  If that's not enough, then descending to warmer air is about all that's left.
Bottom line, at sub-sonic conventional jet aircraft speeds, aerodynamic heating is very much a factor.


text:
What documentation do Airbus/Boeing supply at initial delivery of an aircraft?
What are the Aircraft Documents supplied by Boeing and/or Airbus at first delivery? Do they supply Form 8130 or Certificates of Compliance for every part? Or is the AIR/ARL all that is supplied?


text:
Identify this antique trench art plane
I am a collector of trench art planes in Australia and from time to time come across planes that defy identification. I am currently struggling to identify this model (photos below). The age and appearance of the piece would indicate it was made in the 1930's-1940's, but I can't find a plane of that era which is an appropriate match.
What is it?

This is unlikely to be a copy of a real airplane, much more likely it is the artist's conception of an airplane, so there's likely no answer.

I agree with @GdD - everything about this model screams "Art Deco", so it's likely a stylized/idealized airplane from the 1930s and not based on any particular model. Also, this makes it a bit unlikey to be "trench art". But that's just my opinion of course :)

Wow. This image from the OP's Wikipedia link is... sobering.

The ledge running the full length "below the windows" looks more like a car than a plane.  It would be a stress riser.  I can't think of any production plane with that.

The plane is a die-cast model. Trench art was made from junk found “in the trenches” - metal salvaged from munitions and sometimes their packaging. There’s approximately 0.0 reason to call this one trench art. It’s a sturdy model, evidently designed for mounting on a base, i.e. likely not a toy.

Re "The ledge running the full length "below the windows""-- that's kind of an "art deco" kind of thing I think, to take a design feature that might have existed in one limited area (i.e. cockpit narrower than fuselage below) and extend it across the entire length of the vehicle for a long sweeping look-- or the feature might have been entirely fictional, created to emphasize the vehicle's long lines and given a sense of speed-- +1 on Rob74 comment, likely not any actual aircraft --

I agree with @Kubahasn'tforgottenMonica but as a side note, trench art was sometimes (or maybe even often) incredibly skillfully executed, especially when you think about the material and the conditions it was produced in.

It looks like an aftermarket hood ornament.

From the model I came to conclusion that the aircraft likely was:

British due to it being spotted Australia
Built in 30s as opposed to 40s due to boxy fuselage shape
Civilian or transport plane - due to contouring in upper fuselage
Trimotor due to similarity between engine and nose shapes

With that I looked through Wikipedia's list of 1930s British airliners and found:
Spartan cruiser

Features that match:

General fuselage excluding contouring
The steep vertical profile of the windscreen (somewhat uncommon in other planes)
Engine shape and placement including nose mounted engine being the same but larger than wing mounted engines
Split tail horizontal stabilizer

Features that don't match:

Contouring on top of fuselage - probably mistaken impression by artist delimiting passenger compartment from fuselage accentuated by horizontal paint stripe. I personally thought Ju-52 had that feature but was also mistaken.
Wing shape is different - the model has more forward swept wings
The leading edge of tail horizontal stabilizer is angled instead of perpendicular to fuselage.

With that I was still skeptical about my findings, given that according to Wikipedia there were only 17 such planes without any mention in text connecting them to Australia. That is until I noticed that the picture there was titled "Spartan Cruiser over Melbourne, 1934"
Seeing that I searched the plane number G-ACDW and found its history that places it in Australia:

In the period October to December 1933 a Cruiser II G-ACDW (c/n 3 – Faithful City) was flown by Patrick Windsor Lynch-Blosse, chief pilot of Spartan Airlines, from England to Australia, leaving Lympne on 10 October and arriving in Brisbane, QLD on 29 October after 110 hours flying time.  Lynch-Blosse had previously flown for a short period in New Guinea, and at another stage flew in command of the Avro X Southern Sun in Queensland in 1930.
On 30 October the aircraft was flown to Sydney, NSW, later through Victoria, up the west coast to Derby, WA having circled the continent. It returned to the United Kingdom, arriving on 26 December 1933.  This flight was a long-distance charter and was claimed by the owners to be the longest private charter of its type undertaken.

That means that your artist might have seen the plane in person some time between 29 October 1930 to 26 December 1933 or from pictures some time after that, considering that the longest private charter flight ever might have ended up in local press.

When I saw your model, I immediately thought of the the Boeing 247. It is not an accurate model, but does have the general lines.

The rudder shape slightly resembles the De Havilland designs of that era as do the engine nacelles which look like they would contain either an in-line or a flat engine rather than a radial.
But the fuselage contouring along the window line and towards the nose ahead of the cockpit don't look like any type of plane I know about, so my guess is this was a fanciful take on a twin-engine plane that wasn't modeled on a single type.

Hi Everyone, Thanks so much for your amazing suggestions and research. It is likely we may never know exactly what kind of plane this is meant to be. I agree that the maker was influenced by art-deco style, and may have added deco "speed lines" to the fuselage and engine nacelles to enhance that look. Much appreciated. Cheers, Jason


text:
Why is more angle of bank (AOB) at the best gliding speed giving less altitude loss?
Reading the manual for the T6b (turboprop aircraft single engine), it says different altitude losses during a 360 degree turn, holding 125 kts (the best glide for range speed), power is either dead, so propellers are feathered or is simulated for exercise purposes at 4-6%, which simulates the propellers being feathered.
30° AOB 2000 ft,
45° AOB 1500 ft,
60° AOB 1000 ft
Why  does it seem to have less effect on altitude loss at higher bank angles? Isn’t there less effective lift to compensate for weight during a turn, forcing the aircraft to lose more altitude? I think it’s something to do with the rate of turn. The faster you are turning, the sooner the loss of altitude gets to stop. I’m not sure. How is it possible to lose less altitude with less lift available?

YamchaAviator, would you happen to have an on-line source for that manual?

It probably means it completes the 360 turn faster. So less bank you lose altitude less. However it takes longer to complete a 360 deg turn. So presumably based on this information your better off with a 60 deg quick turn to save energy then babying it. It’s two competing factors. Increased rate of decent due to high bank vs taking longer to compete the turn. With this aircraft and configuration it says the later is more optimal.

It’s NOT saying the aircraft glides better banked. It’s saying less altitude is lost with out power, by completing the turn as quickly as possible roughly.

Also too, if you needed to lose altitude sometimes I beleive a 360 degree turn is used before turning on to final for an un powered landing, similar to the space shuttle. So you can select an bank angle to better precisely achieve the desired altitude.

You have a random altitude. You have excess altitude. You are with in range or even at the start of the unpowered final approach. This would be a case you could do a 360 turn to arrive back at final approach at the lower altitude. By using either a 30, 40, or 60 deg bank angle you can estimate the altitude you will lose. And arrive at the right height. Basically glided landings always rely on excess energy and altitude. But can never have under which is the case you can not make the runway.

When well trained one could argue unpowered final approach is almost more routine and easier then a normal landing. And 360 degree turns are how the plane arrives precisely at the start of final at the precise heading, airspeed, and altitude which is critical. It’s how the space shuttle landed. One can even ask why all finals don’t just use unpowered descents and glide slopes.

If the aircraft arrives high, or low, or too far away from or too close to the runway at the beginning of the final, it compounds all the way to the landing unless a correction is correctly estimated and executed.

If no power but arrive at right heading altitude distance and airspeed on final, it’s merely a visual matter of steering the aircraft down to a point slightly before the threshold and then flairing at the right altitude. Airspeed would be constrained due to lack of power. In theory your air speed would always be good.

I wonder if this trainer turns a little better.

If you have a shallow bank angle, your load factor is low, and thus the aircraft needs to generate less lift. Less lift means less drag, and so a shallow bank angle seems better than a steep bank angle.
However, a shallow bank angle makes for a wide turn. The distance travelled to complete a 360 degrees turn is much longer at shallow bank angles than at steep bank angles. And when you have to travel further, you lose more altitude.
It is more favourable to accept the higher drag penalty of a steep bank angle over a short turn circle circumference, than to coast over a long turn circle with a low drag penalty.
The distance travelled in a 360 degree turn can be found with:
$d = 2\pi \frac{v^2}{g \tan(\phi)}$
with:

$d$ distance travelled
$v$ true airspeed
$g$ gravitational acceleration (~9.81 m/s2
$\phi$ bank angle

( you have to use S.I. units)
This shows that at 30 degrees bank angle, you travel 3 times the distance to complete a full circle compared to a full circle turn at 60 degrees bank angle.

Thats it right there. Awesome. Thank you!

The rate of turn is higher with increased bank angle at a constant speed. At 45deg the rate of turn is 60% higher than at 30deg bank, so there is less time descending in a 360deg turn so less altitude is lost.

There is something inherently dangerous about trying to hold a given airspeed and a steeper and steeper bank.
This a a case where one should consult with a qualified expert on that type of aircraft and, better yet, test these types of turns at altitude with one.
Vbg is typically around 1.3 stall.  In order to maintain adequate vertical lift with a 60 degree bank (2G), airspeed must be at least 1.4 stall, 45 degrees is 1.18, 30 degrees is 1.07.
With less vertical lift (inadequate airspeed), the aircraft will sink and pitch down, increasing airspeed. Trying to maintain adequate vertical lift in steeper banks with higher and higher AoA (and constant airspeed) not only decreases the lift to drag ratio but (obviously) increases the chance of stalling. The safest way to turn at a higher angle is to increase airspeed.
Again, expert advice is recommended here, actual flight data would be preferred.

I would say that at 60 degrees, stall speed increases by 1.4 (as does the airspeed for any other given AoA).  In the T6b specifically, would this raise the stall speed  dangerously close to the wings-level best glide speed?  That seems to be the crucial question of interest.  Also, whether the wings-level best glide speed is way below 1.4 x the wings-level min. sink rate speed-- that also would seem unlikely to end well.  All of which I think is basically your point.  So does this airplane have an unusually high V (best glide), orvwhat

Steep turns and emergency descents are done at much higher airspeeds than Vbg.

Do you think questioner (or actual manual) erred in stating 125 knots is Vbg?  Hmmm..

It certainly should be checked.

Link re T-6b procedures-- does say the clean best-glide airspeed is 125 knots-- I don't think that the other content (altitude loss while turning at various bank angles) is contained in here but too tired to look through in complete detail!  http://www.t6bdriver.com/uploads/6/4/7/7/64775059/q3102_2014_fti.pdf

(Surely must say something about stall speed though.  PS maybe the turns were meant to be done with some flaps down, could that be the key to keeping adequate margin above stall?)

(Pages 7-6 to 7-9 from pdf http://www.t6bdriver.com/uploads/6/4/7/7/64775059/q3102_2014_fti.pdf contain the bank angle / sink rate figures given in the original question, and they are for 125 knots, and as best as I can tell (though it's not completely clear) they are probably for flaps up-- because the implication is that they might be used as early as the high key position-- so-- ??? Still a bit of a mystery to me.  PS the stall speed is not given in this document.

One thing to always remember…  the flying speed you need to produce the required lift is KTAS.  What you will see in the POH is KIAS.  At high banks and high AOAs these can become profoundly different.  In a 45° bank, the calibration error in a 172 is about 6 kts.  But in the similar-winged 182, it is 15 kts.  At 60° of bank the 182 can have 20 kts of calibration error.  This is very important to understand before drawing any aerodynamics conclusions by observing POH guidance on speeds.

@Max so we may conclude we are not holding Vbg in the steep turns?

@Max -- You may well be on to something important to solving our little puzzle here, but I suspect you meant to say KCAS, rather than KTAS?  Surely KTAS is not a consistent guide to stall speed, across a range of various density altitudes, etc.

@quietflyer I think about it this way…  KTAS is the actual speed of air molecules passing over/under my wing and is thus the “fact basis” of how my aircraft will actually perform.  KCAS is the pitot system’s interpretation of that airspeed, which is compromised by the pitot system misinterpreting ram/static ratios at lower pressures and higher temperatures.  And KIAS is further compromised by how the pitot’s physical placement is affected by increasing AOAs.  Wouldn’t I calculate my wing’s lift by using the actual speed of air moving over it, and not my pitot’s flawed approximation of it?

@Max -- only if you are dealing with one particular place and time in the atmosphere (fixed density altitude).  KTAS at stall is very different at sea level then at 20,000'!

@quietflyer - Yes!  Stall speed is always the same for KIAS(KCAS) but varies with density for KTAS.

@quietflyer exactly my point!  It is indeed very different, and if I am going to perform any maximum-performance maneuver that is truly on the very edge of the aircraft’s performance envelope, I do have to account for the atmosphere’s affect on that envelope. I need to know roughly where that edge is, whether I like the answer or not.  Man, I wish we could all get together on a zoom and whiteboard this out together!

In the long run, sink rate is not due to a "shortage of lift" but rather to a shortage of thrust.1 If the angle-of-attack were held constant, then in the very short run, increasing the bank drives a brief shortage of (the vertical component of) lift-- this is involved with the dynamics of causing the flight path to curve down as the airplane accelerates (gains airspeed)-- but that's not what you need to be focusing on. After a very few seconds, the aircraft will have gained enough airspeed to restore the vertical component of lift to essentially its "normal" value. So... it's complicated.
Furthermore, consider this-- in your problem, the specified airspeed is assumed to be fixed.  This means that the angle-of-attack is certainly not fixed.  As the pilot enters the turn, to hold the airspeed constant, he must be increasing the angle-of-attack sufficiently that the vertical component of lift stays (very nearly) constant throughout the turn entry.  So there's no shortage of the (vertical component of) lift to speak of-- not even temporarily, as the aircraft is entering the turn.
So the steeper bank turns are being flown at a higher angle-of-attack than the shallower turns.  But that's never going to offset the effects of the steeper bank angle enough to actually cause a decrease in sink rate.  The key factor is rather that you complete the turn faster when flying at a steeper bank angle, so the altitude loss per degree of turn is decreased.
Nonetheless, the fact that the steeper bank turns are being flown at a higher angle-of-attack does bias the results for minimum altitude loss per degree of turn toward a somewhat higher bank angle than we'd obtain if we specified that the angle-of-attack were held constant (and the steeper bank turns were therefore being flown at a higher airspeed than the shallower turns)--at least so long as we remain on the "front side" of the drag curve.2
Edit:
Actually I initially missed the part about the specified airspeed being the exactly the same as the wings-level best glide speed.  So we're not deep on the "back side" of the drag curve, but we're not way on the "front side" either.  Rather, we are (in the wings-level case) right at the very bottom of the drag curve (i.e. drag is at a minimum).
A key point is that when you are turning, you don't care how far forward you go, you just want to minimize sink rate and maximize turn rate, so there's no reason to fly at best glide speed, you instead want to fly at the min sink rate speed for that bank angle, or arguably even a bit slower, to maximize the turn rate, and therefore minimize the altitude lost per degree of turn.
So starting from the wings-level best L/D (max glide) speed and angle-of-attack, increasing the angle-of-attack as we enter a turn is initially beneficial, in terms of minimizing the altitude lost per degree of turn.
At some point, however, if we continue to increase the bank angle while holding the airspeed constant, we will end up increasing the angle-of-attack so much that we are mushing along near the stall at such a high angle-of-attack that the sink rate, and therefore the altitude lost per circle, will be severely increased.  (In fact, if the bank angle becomes steep enough in relation to the airspeed, we actually reach the stall angle-of-attack if we attempt to hold the airspeed constant by continuing to move the stick or yoke aft-- see this related answer to the present question.)
It seems odd that the aircraft has apparently not yet reached that unfavorable part of the flight envelope when the bank angle has been increased all the way to 60 degrees, with no increase in airspeed beyond the wings-level best glide angle (best L/D) airspeed. For sailplanes and light airplanes, I've typically seen bank angles around 45 degrees recommended to complete a turn with minimum altitude loss, while flying (as best as I recall) at the wings-level best-glide airspeed.
Perhaps there is an unusually wide spread between the wings-level airspeeds (and angles-of-attack) for max glide (best L/D), and for min sink rate, in this aircraft.  Does the manual publish the airspeed for minimum sink rate in wings-level flight, for the same aircraft weight at which the wings-level best glide speed is 125 knots?
Also, consider this-- if we are free to choose any bank angle, is keeping the airspeed right at the wings-level best glide speed really always the very best  strategy for minimizing the altitude lost per degree of turn, or at least a close approximation of such?  Enquiring minds want to know...
Footnotes:

Yes, as has been covered elsewhere on this site, the geometry of the force vector triangle is such that (the vertical component of) lift must be slightly less than weight whenever the flight path is descending (or climbing!) in a steady-state (constant-airspeed) condition, but it's a misconception to think that this discrepancy is what is causing the flight path to descend (or to climb!).  Rather, this discrepancy simply very slightly decreases the airspeed at which the aircraft will be in equilibrium (i.e. the airspeed will be constant), for any given angle-of-attack and bank angle and glide angle (or climb angle!).  In other words this dynamic is very much a sideshow, not the main event.

If the aircraft were initially being flown in slow, "mushing" flight, on the "back side" of the drag curve, then any further increase in angle-of-attack would clearly be detrimental, and if we specified that the airspeed were held constant, we would bias the results toward a lower optimum bank angle for minimum altitude loss per degree of turn, than if we we specified that the angle-of-attack were held constant.  Exactly where on the drag curve we'd need to (initially) be flying so that we'd end up computing the same optimal bank angle to minimize altitude loss per degree of turn regardless of whether we held airspeed constant or held angle-of-attack constant is not completely obvious (and perhaps grounds for an interesting exercise or new ASE question.). It appears that this "break-even" point would correspond to a starting airspeed somewhat slower than the wings-level max-glide (best L/D) airspeed, but well above the wings-level min sink rate airspeed.

if the pilot if pulling back more for more angle of attack because as you mentioned "to hold the airspeed constant, he must be increasing the angle-of-attack sufficiently that the vertical component of lift stays (very nearly) constant throughout the turn entry" , wouldnt that mean that the airspeed is bleeding off? , more pull back less airspeed, right? getting slower than 125 by a lot?

@YamchaAviator -- no-- sorry, don't know how to explain it concisely at the moment--

@YamchaAviator - You are adjusting pitch attitude to maintain airspeed.  If airspeed  becomes low, pitch is lowered increasing rate of descent but increasing airspeed.

I was testing my Pazmany PL-2 homebuilt to see the minimum altitude loss I could achieve following engine failure. I'd dive with engine at idle, pull up into the climb attitude, and as speed decayed past normal climb speed, I'd crank and bank.   45 deg bank got me around 180 deg in something like 250 ft IIRC. But on one try I pulled with a bit too much gusto and zowie it snapped over the top and I found myself pointed at the ground in the space of about a second. That was sobering.

The notion of your first paragraph should be required reading for all pilots, even the most experienced.  The belief that a climb is a result of surplus lift is absolutely pervasive (easily 95+%) among pilots at all levels. Established steady climbs and steady descents are 1.0G maneuvers that do not change the lift produced or the wing loading once established.  Nearly every lift/weight/thrust/drag drawing ever used in flight instruction are not just incorrect but misleading.  And yet as a community we act genuinely puzzled about the frequency of stall/spin fatalities in GA.  It is a travesty.

@JohnK I agree that 45° bank is the magic number for “the impossible turn.”  It’s been a fascination of mine for years and I practice/experiment a lot…  just this year I have easily over an hour of gliding in 45° bank with the stall horn blaring.  In addition to very deliberate use of the rudder, I’ve found another trick--I nose over abruptly so that my transition from climb speed to stall speed is done at about .5G.  My goal is to perform as many degrees of turn as possible with less lift demand and thus lower stall speed.  I now can teardrop my 3100 lb plane in less than 250 feet.

Still could not find stall data for the Texan 2B, but the design seems to be based on the Pilatus PC-9.  I wonder why the Air Force doesn't use this one as a trainer.  More wing area than the Texan 2.  I guess "real pilots" don't stall with all that power, right?  Might get around faster at 60 degrees, but how much altitude is lost recovering to wings level?

I wonder if one or more of the altitude-loss-per-turn figures in the manual might simply be wrong, at least given the apparent specified constraints (125, clean.)

@quietflyer I would not rule this out at all.  Cessna 182 RGs have a significant (10 knot) typo error in several entries in the POH stall table, and surprisingly has never revised the POH.